252 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



The outer lamina of the parietes is pitted internally, as may be seen 

 by looking in the outer row of basal pores. This produces the dis- 

 tinctly beaded riblets of the worn exterior. The same structure is 

 found in some other subspecies of T. squamosa, but much less dis- 

 tinctly developed. 



A form from West Africa in the National Museum , and Capo Palmas in the collection of the Academy 

 of Natural Sciences of Philadelphia, closely resembles the oriental T. s. squamosa. The specimens seen, 

 about 20, are small, the largest 16 mm. in diameter. The radii are generally distinct, though narrow, ana 

 the eroded ribs of the parietes are conspicuously beaded. The pores are coarse, in two or three irregular 

 rows, and the wall is not very thick, thus ditfering from typical squamosa. The sheath is green. The long 

 adductor ridge of the scutum unites with the articular ridge above, but there is no cavity perforating to 

 the apex, such as is described for T. scrrata. 



TETRACLITA SQUAMOSA JAPONICA, new subspecies. 



Plate 58, figs. 1 to 3r/, 



1911. Tetrad! t a porosa vai'. nigrescens KRUGER, Beitriige zur Cirripedien- 

 fauua Ostasiens, p. 61, pi. 4, fig. 41c. 



Type. Cat. No. 580GO, U.S.N.M., from Ayukawa, Japan. 



The surface is wholly removed in adults, deep or dark purplish- 

 gray or deep mouse-gray; sutures distinct or obliterated; no crenu- 

 lation on the flat radial faces ; pores of medium or small size ; sheath 

 generally of unusual length, but sometimes short, vinaceous slate to 

 dull violet black. Orifice usually rather large in adults. 



Scutum with rather inconspicuous growth-ridges. Inside varying 

 shades of slate-violet. Articular ridge small and projecting or re- 

 flexed very little. Articular furrow small. The adductor ridge is 

 strong and extends nearly to base and apex ; a deep but narrow fur- 

 row separates it from the articular ridge throughout. The crests 

 for the depressor muscles are strongly developed. The rather 

 broadly inflexed occludent border has four or five strong, oblique 

 teeth (pi. 58, fig. 3). 



The tergum is rather narrow, its median width contained two and 

 one-third to two and one-half times in the length. Externally it has 

 a slight depression running to the spur, which is removed a little 

 from the scutal border; growth-ridges narrow and rather conspicu- 

 ous. Inside nearly white, not bicolored. Basal margin oblique, but 



